Condition Analysis
AI-powered assessment using site data and 14-day weather history
The rock has had roughly 4 dry days since the last significant rain on August 20th (7.2mm), but a cluster of wet days from August 16–21 deposited ~15mm in total, and humidity has remained high (79% average over the last week). The south/south-west aspect and exposed position have aided drying, and conditions may be acceptable on upper, well-drained faces this afternoon — but visual assessment is essential before committing, especially with heavy rain arriving tomorrow.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The Calf boulder and other freestanding blocks dry faster than the main quarried faces due to air circulation on all sides, so these may be in better condition than the buttress routes.
- The crag sits on open moorland at 260m; boggy ground around the base can indicate residual moisture in the rock even when surfaces appear dry.
- Heavy rain is forecast from August 27–30 (over 40mm total), meaning today may be the last feasible climbing window for nearly a week.
- Lower sections of the main crag and any north-facing arêtes or corners will retain moisture longer despite the overall favourable aspect.
Warnings
2
- Heavy rain (40mm+) is forecast from August 27–30; the rock will be fully re-saturated and unsafe for climbing for several days after.
- Do not assume surface-dry rock means internally dry rock — the recent wet spell and high humidity mean internal moisture may still be present.
Reasoning
The most significant recent rain was 7.2mm on August 20th, preceded by several light-rain days totalling ~15mm from August 16–21; four essentially dry days since (Aug 22–25) with moderate temperatures and wind have allowed substantial surface drying, but high average humidity (79%) has slowed internal moisture loss.
The south/south-west aspect and exposed, windy position (averaging ~17 km/h) have aided evaporation during the 4+ dry days, and summer temperatures around 18°C are adequate — this is approaching the threshold for adequate drying after moderate rain, though the cumulative wet spell makes full internal drying uncertain.
After ~15mm over five days followed by only four drying days at moderate temperatures and elevated humidity, some internal moisture likely remains in thicker sections and lower faces, posing a moderate risk of grain loosening under load.
Mid-to-late summer provides reasonable drying conditions with long daylight hours and warm temperatures, though the current unsettled spell with high humidity is below-average for the season.
Contributing Factors
6
Approximately 15mm fell between August 16–21, with 7.2mm on August 20th alone, saturating the rock after an earlier dry spell.
August 22–25 were dry with moderate wind and temperatures around 18°C, allowing significant surface and partial internal drying.
The south/south-west facing, exposed moorland position maximises solar gain and wind drying, accelerating moisture loss compared to sheltered or north-facing sites.
Average humidity of 79% over the past week slows evaporation and may have left internal moisture trapped despite surface drying.
A trace of rain (0.1mm) forecast around 18:00 today adds slight uncertainty, though the amount is negligible.
Over 40mm is forecast across August 27–30, which will fully re-saturate the rock and close the window for the rest of the week.
Recommendations
3
- If climbing today, visually inspect the rock and check ground moisture at the crag base — if the soil is damp or the rock darkens when touched, do not climb.
- Prioritise freestanding boulders like the Calf and upper, well-drained faces which will have dried fastest; avoid lower buttress sections and any seepage-prone lines.
- Be aware that heavy rain arrives tomorrow — this is likely the last viable window until at least September 1st or later, so do not rush into poor conditions out of urgency.
Previous Analyses
Marginal — Assess Conditions
65%
57 days ago
Three consecutive dry days with moderate temperatures and decent wind on an exposed, south-facing crag have likely dried the rock after the recent wet spell (14.9mm over Aug 16–21), but humidity has remained fairly high (averaging 79% over the last week) and the last significant rain (7.2mm on Aug 20) was only four days ago. Conditions are probably climbable today, especially on exposed upper faces, but a visual and tactile check on arrival is essential before committing — and a major wet spell arrives from tomorrow onwards.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The Calf boulder and other freestanding blocks dry faster on all sides than buttress faces backed by the hillside, which can retain seepage from the moor above.
- The south/south-west aspect and exposed moorland position give Cow and Calf above-average drying, but low-level problems and north-facing arêtes on the Calf boulder will hold moisture longer.
- A prolonged wet spell of 80mm is forecast from Aug 25–29, which will leave the crag unsuitable for climbing well into early September.
- The moorland drainage above the crag can feed seepage lines on the main quarry walls long after rain has stopped — check for dark streaks before climbing trad routes.
Warnings
2
- A major wet spell (67+ mm over Aug 27–28 alone) begins tomorrow — the crag will be thoroughly saturated and unsafe for climbing for an extended period afterwards.
- Even today, sheltered or north-facing faces on the boulders and quarry walls may still be damp internally despite appearing surface-dry.
Reasoning
The most significant recent rain was 7.2mm on Aug 20 followed by 0.5mm on Aug 21, giving roughly 2.5–3 full dry days; the exposed S/SW aspect and moderate wind aid drying, but the rock may still hold residual internal moisture from the cumulative 14.9mm that fell over Aug 16–21.
Three dry days with temperatures reaching 17–19°C, humidity around 71–77%, and westerly winds of 10–16 km/h on an exposed south-facing crag should be sufficient for surface and near-surface drying after the moderate rainfall, though full internal drying of deeper-seated moisture is less certain.
Structural risk is moderate — the rock has had enough drying time that surface holds should have regained most strength, but any areas with persistent seepage or sheltered aspects could still be compromised.
Mid-summer conditions with reasonable temperatures and long daylight hours are favourable, though the recent spell has been cooler and damper than average for August, and a very wet period is imminent.
Contributing Factors
5
No measurable precipitation since Aug 21 (0.5mm trace), giving approximately 72 hours of drying time on an exposed crag.
The south-facing, wind-exposed position on open moorland maximises solar radiation and airflow, significantly accelerating drying compared to sheltered or north-facing venues.
Average humidity over the past week has been 79%, which slows evaporation and limits how effectively the rock can shed internal moisture.
Approximately 14.9mm fell over Aug 16–21, with the heaviest single day being 7.2mm on Aug 20, meaning the rock absorbed a moderate soaking relatively recently.
Over 80mm of rain is forecast from Aug 25–29, making today the last viable climbing window for potentially a week or more.
Recommendations
3
- Today offers the best window — head out this afternoon when humidity is lowest (51–58%) and wind is up (15–17 km/h), and physically check the rock with your palm before climbing.
- Avoid lower sections of the quarry walls and any routes with visible seepage streaks, as these will be the last areas to dry.
- Do not plan to climb at Cow and Calf from Aug 25 onwards — the forecast 80mm of rain will require at least 3–5 dry days of good conditions afterwards to become safe again.
Marginal — Assess Conditions
62%
58 days ago
After a wet spell culminating in 7.2mm on August 20th and lighter rain on the 21st, Ilkley has had roughly 2 dry days with moderate temperatures but relatively high humidity (75–79%). The south/south-west aspect and exposed position will have aided drying, but given the cumulative recent moisture and average humidity in the low-to-mid 80s over the past week, a visual assessment on arrival is strongly recommended before committing to climb.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The Calf boulder and other freestanding boulders tend to dry faster than the main quarried faces due to all-round air circulation, but seepage can linger in horizontal breaks and cracks.
- The S/SW aspect and exposed moorland position make this one of the faster-drying Yorkshire gritstone venues, but the recent week has seen persistently high humidity (83% average) which slows evaporation significantly.
- Very heavy rain is forecast for August 27–28 (nearly 70mm combined), which will thoroughly saturate the rock and require extended drying afterwards — climbers should prioritise the next 2–3 days if conditions check out on arrival.
- The base areas and lower sections of the quarried faces will retain moisture longest; check the ground at the crag base as a proxy for internal rock moisture.
Warnings
2
- Do not climb on any rock that feels cool or tacky to the touch — surface-dry gritstone can still be dangerously weakened internally.
- Very heavy rain (42mm + 27mm) is forecast for August 27–28; do not climb during or immediately after this event — the rock will need extended drying.
Reasoning
The most significant recent rain was 7.2mm on August 20th followed by 0.5mm on August 21st, with only 2 full dry days since — the rock has had limited drying time and may still hold internal moisture despite appearing surface-dry.
The S/SW aspect and exposed position are favourable for drying, but temperatures have been modest (mid-to-high teens °C), humidity has averaged 83% over the past week, and wind has been light-to-moderate, meaning drying has been slower than ideal for the 2 days available.
Given that the 7.2mm event was only 3 days ago and preceded by several days of lighter rain totalling ~15mm in the last week, there is a moderate risk that internal moisture levels remain above the ~1% threshold where strength loss begins.
Mid-to-late August is generally a reasonable time for gritstone climbing, but the current unsettled pattern with high humidity is reducing the usual summer drying advantage.
Contributing Factors
7
7.2mm fell on August 20th, preceded by several days of lighter rain (2.5mm, 1.8mm, 2.9mm on the 17th–19th), meaning the rock entered this drying window already well-saturated.
With just 2 consecutive dry days since the last measurable rain, the minimum 24–48 hour guideline for light rain is only marginally met, and the cumulative saturation from the preceding wet spell demands more caution.
The south and south-west facing rock receives good solar radiation during summer days, which is the strongest drying advantage this crag has.
The exposed, open moorland setting allows sustained wind to move moist air from the rock surface, accelerating drying compared to sheltered or wooded crags.
Humidity has averaged 83% over the past 7 days and remains around 75% today, significantly reducing net evaporation rates from the rock surface.
Temperatures around 17–18°C are adequate but not strongly driving evaporation; the warm spell of 29–32°C seen a week earlier would have been far more effective.
A combined ~69mm of rain is forecast for August 27–28, which will thoroughly re-saturate the rock and close the current drying window entirely.
Recommendations
3
- Visit today or in the next 2–3 days to take advantage of the drying window before the heavy rain forecast for August 27–28, but visually and physically assess the rock on arrival — check that the ground at the base of the crag is completely dry.
- Focus on the upper, south-facing sections of the Calf boulder and other well-exposed freestanding blocks, which will have dried fastest; avoid lower quarried faces and any areas with visible seepage or dark patches.
- After the heavy rain expected on August 27–28, allow a minimum of 3–4 days of dry weather before returning, and longer if humidity remains high.
Do Not Climb
35%
59 days ago
The crag has received significant recent rainfall — 7.2mm on August 20th followed by 0.5mm on the 21st — with only one full dry day (today) since. Despite the south-facing aspect and exposed position, humidity has been high (averaging 83% over the past week) and temperatures cool (averaging 13.5°C), meaning drying conditions have been poor. The rock is very likely still holding internal moisture.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The Calf boulder and surrounding blocks have complex geometry with horizontal breaks and ledges that trap water, extending drying times beyond what aspect alone would suggest.
- The open moorland setting means the crag benefits from good wind exposure, but recent winds have been light (11–14 km/h) and humidity high, limiting effective drying.
- Seepage can persist at the base of the main Cow buttress and in horizontal cracks across the Calf boulder for days after heavy rain, even when upper faces appear dry.
- The moorland peat soil retains water and can feed moisture back to the rock base; check for damp ground at the crag foot as a proxy for internal rock moisture.
Warnings
2
- The rock surface may appear dry while the interior remains saturated — do not rely on visual or touch assessment of the face alone; check sheltered cracks and the crag base.
- Climbing on internally damp gritstone risks permanent hold breakage and route damage that cannot be repaired.
Reasoning
7.2mm fell just two days ago on the 20th with a further 0.5mm on the 21st, and with only one dry day since, the gritstone is almost certainly still holding significant internal moisture despite any surface drying.
Drying conditions have been poor — average humidity of 83%, temperatures around 13–17°C, and light winds of 11–14 km/h over the past two days offer limited evaporative potential, even with the favourable south/south-west aspect.
Gritstone weakens significantly with even low saturation levels, and with only ~24 hours of mediocre drying since the last rain, holds are at elevated risk of breakage under climbing loads.
Late August should offer reasonable drying conditions, but this week has seen an unusually cool, humid, and wet spell that has kept the rock saturated for an extended period.
Contributing Factors
7
7.2mm fell on August 20th — a significant soaking for porous gritstone — followed by 0.5mm on the 21st, leaving very little drying time.
Only one full dry day has elapsed since the last rain, well short of the minimum 48–72 hours recommended after heavy rain on gritstone.
Average humidity over the past week has been 83%, severely limiting evaporation rates and prolonging internal moisture retention.
Average temperatures of 13.5°C over the past week are below seasonal norms, slowing evaporation from the rock.
The south and south-west facing aspect provides good solar radiation during available sunshine hours, aiding surface drying.
The open moorland setting allows wind to reach the rock from most directions, though recent wind speeds have been modest at 11–14 km/h.
15.4mm has fallen in the past 7 days across multiple events, meaning the rock has had little chance to dry out fully between showers.
Recommendations
3
- Wait at least until August 24th — a minimum of 48 hours of dry weather with improving conditions — before considering climbing here.
- Before climbing, check for damp peat at the base of the crag and feel horizontal breaks and crack lines on the Calf boulder for residual moisture.
- If you visit and conditions look marginal, consider non-porous alternatives such as limestone venues in the Yorkshire Dales instead.
Do Not Climb
35%
60 days ago
The rock at Cow and Calf has received significant rainfall over the past five days (15.1mm in the last week, including 7.2mm on Aug 20 and smaller amounts on Aug 17–19), with today still showing a trace of precipitation and zero consecutive dry days. Despite the exposed S/SW aspect, insufficient drying time has elapsed and conditions are too uncertain to recommend climbing.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The Calf boulder and main buttresses face S/SW and are well-exposed to wind, meaning they dry faster than many gritstone venues — but the recent multi-day wet spell (Aug 17–20) will have allowed deep saturation that surface drying alone won't resolve.
- Seepage lines on the Calf boulder and lower walls of the Cow can persist for days after heavy rain, particularly around the back and base of the Calf where drainage collects.
- The open moorland setting at 260m means the crag benefits from wind-assisted drying, but the cool temperatures (averaging only ~14°C this week) and high humidity (82% average) are significantly limiting evaporation rates.
- The ground at the base of the crag is a useful proxy — if the peat and moorland soil around the boulders is still damp, the gritstone is almost certainly still holding internal moisture.
Warnings
2
- Gritstone that has been wet for multiple consecutive days (as here) can appear surface-dry while remaining dangerously weakened internally — do not rely on touch alone.
- Hold breakage risk is elevated after prolonged saturation; even familiar holds may be compromised.
Reasoning
With 7.2mm falling on Aug 20, smaller amounts on Aug 17–19 (totalling ~7.2mm before that), and a trace today (0.2mm), the rock has had essentially no dry time and is very likely saturated internally despite any surface drying.
The S/SW aspect and exposed position are favourable for drying, but with only a few hours of potential drying since yesterday's 7.2mm and today's continued drizzle, combined with cool temperatures (~14°C) and high humidity (76–87%), the rock will not have dried meaningfully.
Gritstone that has been repeatedly wetted over several days (Aug 16–20) will have achieved deep saturation, and climbing now risks hold breakage and accelerated grain loss — the 10–50% compressive strength reduction applies.
Summer conditions should normally favour drying, but this has been a notably cool, humid, and unsettled spell for August, meaning drying rates are well below seasonal norms.
Contributing Factors
6
7.2mm fell yesterday (Aug 20) on top of 7.7mm over Aug 16–19, creating a prolonged wetting period that will have deeply saturated the porous gritstone.
Today (Aug 21) still shows 0.2mm of precipitation, meaning there has been no meaningful drying window since the last significant rain.
Average humidity over the last 7 days is 82%, with today at 76%, severely limiting evaporative drying even on this exposed site.
Temperatures have averaged only 13.9°C over the past week with today's max at just 14.7°C, well below summer norms and insufficient to drive rapid drying.
The site's south-facing exposed position is the most favourable possible for drying, and will help once a genuine dry window arrives.
Winds of 13–14 km/h today aid surface evaporation, though this is less effective when humidity is high.
Recommendations
3
- Do not climb today — wait for at least 48 hours of dry weather with declining humidity before visiting.
- Check the ground and base of the Calf boulder on arrival: if the peat or soil feels damp, the rock is still holding internal moisture and should not be climbed.
- The best window this week looks to be Aug 23–24 if the forecast holds dry; arrive later in the day to allow maximum sun-drying time on the S/SW faces.
Do Not Climb
92%
61 days ago
The rock is currently wet and should not be climbed. Today has seen persistent light rain through the morning on top of a very wet preceding week (14.3mm in 7 days including 5.8mm today), with high humidity preventing any meaningful drying. At least 48 hours of dry weather from tomorrow afternoon is needed before conditions can be reassessed.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The Calf boulder and main faces are S/SW-facing and exposed, which will aid drying once the rain stops, but the current saturation from repeated wet days means even these well-aspected surfaces need extended dry time.
- Lower sections of the Calf boulder and routes near the base of the quarry walls will retain moisture longest due to gravity-driven drainage concentrating water at the bottom.
- The exposed moorland setting means wind will be a strong drying ally once dry weather arrives, but today's northerly wind combined with near-constant cloud cover and high humidity is doing little to help.
- The sequence of wet days from Aug 16–20 (cumulative ~14mm with no meaningful dry breaks) means the gritstone is likely approaching significant internal saturation despite individually modest rainfall totals.
Warnings
2
- Climbing on saturated gritstone risks permanent hold breakage and route damage — the rock may lose 30–50% of its compressive strength when wet.
- The surface may appear dry before the interior has dried; do not be fooled by a dry-looking surface after only one day of dry weather following this wet spell.
Reasoning
The gritstone is almost certainly saturated internally after five consecutive days of rainfall (Aug 16–20, totalling ~14mm) with no dry break exceeding 24 hours and average humidity around 85%.
There has been essentially zero effective drying since Aug 15; today's rain continued through the morning with 100% cloud cover and humidity above 80%, and even the S/SW aspect and exposed position cannot compensate for continuous wetting.
With the rock likely at high internal saturation, compressive strength will be significantly reduced (potentially 30%+ loss), making hold breakage and surface damage a real risk on this well-trafficked gritstone venue.
Mid-August should offer reasonable drying conditions, and the forecast shows improving weather from Aug 22, but the current wet spell must be given adequate time to dry out before climbing resumes.
Contributing Factors
6
5.8mm of precipitation today with intermittent showers through the morning ensures the rock surface is currently wet.
Five consecutive days of rain from Aug 16–20 totalling ~14mm with no meaningful drying window means deep internal saturation of the gritstone.
Average humidity over the last 7 days has been 82%, with today peaking at 98%, severely limiting evaporative drying.
The S/SW aspect and exposed moorland position will promote rapid drying once dry, sunny weather arrives from Aug 22 onwards.
Temperatures averaging only 15°C over the past week with today maxing at just 15°C slow the rate of moisture loss from the rock.
The exposed hilltop position with consistent winds of 14–16 km/h will help accelerate surface drying once precipitation stops.
Recommendations
3
- Do not climb today — the rock is actively wet and internally saturated from five days of repeated rainfall.
- The earliest realistic window to assess conditions is the afternoon of August 23, after approximately 48 hours of forecast dry weather with moderate temperatures.
- Before climbing, check the base of the Calf boulder and lower wall sections — if the ground or rock base feels damp, the interior is still wet and you should wait.
Do Not Climb
95%
62 days ago
The rock is currently wet from today's rain (8mm) on top of several days of intermittent precipitation, and a major 25.8mm rainfall event is forecast for tomorrow. Conditions are clearly unsuitable for climbing today and will remain so for at least the next two to three days.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The Calf boulder and surrounding blocks are exposed to the full force of westerly rain, meaning all faces will have received direct wetting from the recent showers.
- The S/SW aspect and exposed position will aid drying once clear weather arrives, but the north-facing sides of boulders and lower sections of the Calf will hold moisture much longer.
- Seepage lines and horizontal breaks on the main Cow crag can weep for days after heavy rain, particularly on the lower tier.
- Open moorland setting means waterlogged peat and turf at the base can indicate residual rock moisture — if the ground squelches, the grit is still wet inside.
Warnings
2
- Climbing on wet millstone grit causes permanent, irreversible damage through hold breakage and grain loosening — do not climb if there is any doubt.
- Tomorrow's 25.8mm rainfall will heavily saturate the rock; surface-dry appearance after just one day is deceptive and does not indicate safe internal conditions.
Reasoning
The rock has received 8mm today on top of cumulative light rain over the past few days (2.5mm on Aug 17, 1.3mm on Aug 18), so internal moisture levels are elevated and the gritstone will be thoroughly wetted.
There has been no meaningful drying window — rain fell this morning through to midday, and while the afternoon clears briefly, humidity remains high (60–70%) with moderate wind, providing only superficial surface drying before more rain tonight and a heavy 25.8mm event tomorrow.
With the rock absorbing repeated wetting over recent days and a major rainfall event imminent, climbing now or in the near future risks significant hold breakage and grain loosening on this porous millstone grit.
Mid-August should offer decent drying conditions in theory, but the current unsettled spell with cool temperatures (15–17°C) and high humidity is limiting evaporation rates well below summer norms.
Contributing Factors
6
8mm of precipitation today with rain through the morning and further showers forecast tonight means the rock is actively wet.
A forecast 25.8mm event on August 20th will thoroughly saturate the gritstone and reset any drying progress to zero.
12.3mm over the last 7 days with no consecutive dry period means the rock has had no chance to dry internally.
Average humidity of 78% over the last week severely limits evaporation and drying rate even when rain stops.
The exposed, south-west-facing position will accelerate drying once the rain clears from August 21st onwards.
Winds of 14–15 km/h from August 21st onwards will help move moist air away from the rock surface during the drying window.
Recommendations
3
- Do not climb today or tomorrow — the rock is wet and will be re-saturated by tomorrow's heavy rain.
- Target August 23rd at the earliest for a visit, allowing 48+ hours of dry weather after the last rain, but check conditions on arrival.
- When you do visit, check the base of the crag and horizontal breaks for dampness — if the peat at the base is soggy or breaks are seeping, the grit is still too wet inside.
Do Not Climb
92%
63 days ago
The rock is currently wet from ongoing intermittent rain today (2.6mm) following rain on the 16th and 17th, with high humidity and full cloud cover preventing any meaningful drying. Tomorrow brings further rain (1.9mm) and the 20th sees heavy rain (10.3mm), so conditions will not improve until at least the 22nd.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The Cow and Calf's exposed S/SW aspect normally aids drying, but persistent 100% cloud cover today and tomorrow eliminates the solar advantage entirely.
- The large Calf boulder and surrounding blocks have horizontal surfaces that pool water; these seep into cracks and take longer to dry than vertical faces.
- Being open moorland at 260m, the strong westerly winds (25-28 km/h) will help surface drying once rain stops, but internal moisture from three consecutive days of rain needs more time.
- The base areas around the Calf boulder and the quarried faces can retain moisture in the peat and soil, indicating internal rock dampness — check ground moisture as a proxy before climbing.
Warnings
2
- Active rain and saturated gritstone make climbing today dangerous — hold breakage risk is high and damage to routes is likely.
- Heavy rain forecast for the 20th (10.3mm) will fully re-saturate the rock; do not assume a brief dry spell tomorrow afternoon means the rock is safe.
Reasoning
The gritstone is currently wet from intermittent rain today (2.6mm total) on top of 1.6mm yesterday and 0.5mm on the 16th — three consecutive days of precipitation have kept the rock saturated.
Despite the exposed aspect and moderate winds, 100% cloud cover and 80-95% humidity today have provided essentially zero effective drying; the S/SW aspect advantage is nullified without sunshine.
With three days of cumulative wetting totalling ~4.7mm and no drying window, the gritstone will have significant internal moisture and reduced compressive strength — climbing risks hold breakage and permanent surface damage.
Mid-August should offer good drying potential, but this unsettled spell with below-average temperatures (14-16°C) and high humidity is limiting evaporation rates significantly.
Contributing Factors
6
Intermittent showers throughout today have deposited 2.6mm with further drizzle forecast into the evening, keeping the rock surface wet.
Rain on the 16th (0.5mm), 17th (1.6mm), and 18th (2.6mm) totalling 4.7mm means the gritstone has had no opportunity to begin drying.
100% cloud cover all day eliminates solar radiation that the S/SW aspect would otherwise exploit for drying.
Humidity ranging 74-97% today severely limits evaporation rates even with moderate wind.
Westerly winds of 20-28 km/h across the exposed moorland will assist surface drying once precipitation ceases, but cannot overcome current moisture input.
Tomorrow brings another 1.9mm and the 20th brings heavy rain (10.3mm), resetting any drying progress entirely.
Recommendations
3
- Do not climb today or tomorrow — the rock is actively wet and further rain is forecast.
- The earliest realistic window is the 22nd August after two full dry days post the heavy rain on the 20th, but even then assess conditions carefully on arrival.
- Check the ground at the base of the Calf boulder before committing — if the peat and soil feel damp, the rock interior is still holding moisture.
Do Not Climb
80%
64 days ago
The rock received light rain yesterday (1.7mm on 16th) and again early today (1.5mm so far), with very high humidity (89–98%) and 100% cloud cover suppressing drying throughout the day. With 5.7mm forecast tomorrow and further rain on the 19th and 20th, conditions are unsuitable now and will remain poor for several days.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The Calf boulder and main crag face south/south-west, which normally aids drying, but today's 100% cloud cover negates any solar benefit.
- Cow and Calf sits on exposed open moorland at 260m, so wind-driven drying can be effective, but today's winds are very light (2–9 km/h) until late afternoon, limiting evaporation.
- Seepage lines on the Calf boulder and lower buttresses can persist well after surface rock appears dry, especially after consecutive days of light rain like the current pattern.
- The popular lower-level boulder problems around the base of the Calf tend to stay damp longest as moisture drains downward through the gritstone.
Warnings
2
- Gritstone can appear surface-dry while still dangerously weakened internally — do not be misled by any brief dry spells this afternoon.
- Climbing on damp gritstone causes permanent, irreversible damage to holds and route surfaces at Cow and Calf.
Reasoning
Light rain fell on the 16th (1.7mm) and again in the early hours of today (1.5mm total), and the rock is almost certainly still holding internal moisture given humidity has been 89–98% all day with no meaningful drying window.
Despite the S/SW aspect, 100% cloud cover all day, near-calm winds (2–9 km/h through mid-afternoon), and humidity consistently above 77% mean negligible net evaporation has occurred since the last rain.
Gritstone loses significant compressive strength even at low saturation levels; climbing on rock that received rain only hours ago risks grain loosening, hold breakage, and permanent surface damage.
Mid-August should be a prime climbing window, but this unsettled spell with recurring light rain, high humidity, and cool temperatures (16–18°C) is creating poor drying conditions atypical for summer.
Contributing Factors
5
1.7mm fell yesterday and 1.5mm today including overnight showers, with further light rain possible at 23:00 tonight, keeping the rock wet.
Humidity has ranged from 77–98% throughout today with 100% cloud cover, virtually halting evaporative drying.
Winds have been only 1–9 km/h for most of today, far too light to drive significant moisture removal from the exposed rock surface.
5.7mm is forecast tomorrow, 1.2mm on the 19th, and a heavy 9.6mm on the 20th, meaning no meaningful drying window for at least 4 days.
Temperatures around 16–18°C are warm enough to support drying in principle, but are negated by the humidity and cloud cover.
Recommendations
3
- Do not climb today — the gritstone is almost certainly still damp internally from overnight and yesterday's rain, and humidity is too high for drying.
- The earliest realistic opportunity may be the 22nd or 23rd of August, after the heavy rain on the 20th clears and dry weather establishes.
- If visiting the area, use this week for non-porous venues (limestone or whinstone) instead, and return to Cow and Calf once two full dry days have passed.
Marginal — Assess Conditions
65%
65 days ago
The rock had an excellent extended dry spell from August 8–15 (8 days, with only a trivial 0.1mm on the 10th), but today's 0.7mm of rain breaks the dry streak. Given the S/SW aspect, exposed position, and the deeply dried state of the rock prior to today's light shower, the surface is likely only lightly dampened — but climbers should visually confirm dryness on arrival, especially on lower sections and any north-facing features.
Based on weather conditions only — does not cover bird nesting restrictions or other access issues.
- The Calf boulder's various faces have different aspects; south-facing sides will dry fastest while any north-facing or sheltered sides may retain today's moisture longer.
- The extended hot, dry spell from August 8–15 (peaking at 32°C on the 13th) will have thoroughly dried the rock internally, meaning today's light 0.7mm shower is unlikely to have penetrated deeply.
- The open moorland setting and exposed position at 260m mean wind-driven drying is very effective, but the same exposure means light rain and mist can re-wet the surface quickly.
- Incoming rain on August 18–19 (3.0mm + 2.1mm) will reset drying conditions, so the next 24–36 hours represent a window before conditions deteriorate.
Warnings
1
- Do not climb if any dampness is visible or the rock feels cool/clammy to the touch — even 0.7mm can leave gritstone surface-wet in sheltered spots.
Reasoning
Today's 0.7mm of rain fell on rock that was deeply dried after an 8-day dry spell with warm temperatures (up to 32°C) and low humidity (53–76%), so internal moisture levels should remain low with only surface dampness from the light shower.
The S/SW aspect and exposed position with 15.5 km/h westerly winds today should allow the 0.7mm surface wetting to evaporate within hours to overnight, though 77% humidity slows this slightly.
Structural risk is very low — the rock was thoroughly dried over the preceding week-plus, and today's trace rainfall is insufficient to cause meaningful re-saturation of the pore structure.
Mid-August is peak summer season with good daylight hours and generally warm temperatures; no freeze-thaw concerns at this time of year.
Contributing Factors
5
Eight essentially dry days (Aug 8–15) with temperatures reaching 32°C deeply dried the rock, leaving it in excellent baseline condition before today's shower.
0.7mm of precipitation today breaks the dry streak, wetting the rock surface and requiring visual confirmation before climbing.
The south/south-westerly facing, exposed site receives strong solar radiation and consistent wind, promoting rapid surface drying after light rain.
Today's relatively high humidity of 77% moderately slows evaporation rates compared to the drier conditions earlier in the week.
Rain is forecast for August 17–19 (totalling ~5.8mm), meaning conditions will deteriorate and any current dry window is narrow.
Recommendations
3
- If climbing today or early tomorrow, visually inspect the rock surface and check that the ground at the base of the crag is sandy-dry — if it's still damp, wait.
- Prioritise upper sections and south-facing walls of the Calf boulder, which will dry fastest after today's light shower.
- Be aware that conditions will worsen from August 18 onward with forecast rain; plan sessions for the current window if the rock passes a visual dryness test.
Climbing Outlook